In most cases, extending the grazing season is defined by stockpiling grass during the growing season for use during periods with no growth. However, one can also define extended grazing as supplemental crops planted on acreage that is typically not grazed and the use of grain crop aftermath, such as cornstalk fields.
The primary purpose of extended grazing is to reduce the amount of stored feed that is used. Recall that all hay and other stored forages (even those made on the farm) have a higher cost than grazed forage. Additionally, the nutritional value of standing forage will generally be higher than from hay; the reduction and even elimination of hay harvest on the farm is possible; and facilities for storage and feeding can be reduced.
As described by Ball et al. (2008), many different cool-season grasses can be stockpiled. The species of choice is usually tall fescue. Tall fescue fits into a perennial, cool-season grazing system very well, and it provides good forage in spring and summer, particularly if it is managed to prevent seed head formation. Studies in Pennsylvania (Comerford et al., 2005) indicated that fescue produced high-quality feed during fall growth, with some crude protein samples exceeding those from alfalfa. In addition, fescue has a waxy layer on the leaf and stem that tends to protect the plant from frost and snow damage, and the nutritional value can be maintained well into the winter.
In the Comerford et al. (2005) study, dry matter (DM) accumulation of stockpiled fescue pastures ranged from 1,000 to 1,500 pounds of dry matter per acre across three years. These values can form a benchmark for how much land should be diverted to stockpiling and/or how many grazing days can be expected from a fixed acreage. In this case, using a 1,000-pound beef cow as the standard, this represents enough forage for about 55 cows per acre per day. Further, if one uses a value of $80 per ton for hay, the value of hay savings for those 55 cows is about $50 per day when grazing stockpiled forage instead of eating hay - without having to climb on the tractor on a cold morning to feed the cows.
There are some features of stockpiling that have to be considered:
- The herd may need to be smaller on a fixed acreage because the diversion of grazing acreage will leave fewer acres available during the growing season.
- Endophyte-free or MaxQ varieties of fescue should be used to prevent the effects of fescue toxicosis.
- For best results, fescue should be grazed or cut closely and diverted about August 1 in the mid-Atlantic region and have nitrogen fertilizer applied to provide autumn growth and forage quality.
- Strip-grazing stockpiled forage is the most effective and efficient way to manage grazing.
In some cases, land may be available to plant supplemental crops that can be used for grazing. This is a typical process in the High Plains of the U.S. when wheat crops are grazed in the late fall. In the mid-Atlantic region, there are a number of choices. In some cases brassicas, such as rape or turnips, are used. Small grains, particularly rye, can be planted following silage or early-harvested soybeans and small grains. And if enough acreage is available, annual grasses such as Sudan grass can be used, planted in midsummer and grazed in autumn (while stockpiled pastures are growing) before frost.
A major disadvantage of using supplemental crops for beef cattle is the cost. In the spring-calving cow herd typical of this region, the nutritional needs of the nonlactating cow in its first trimester of pregnancy are at their lowest point of the production cycle. The cost of seed, fertilizer and driving tractors over the land must be balanced with a significant cost savings. In the 2005 Pennsylvania study, it was shown that annual plants were not cost-effective to fit into most beef cattle grazing systems in the region.
As described by Ritchie (1988), there are some issues with grazing stalk fields that must be considered:
1. One acre can carry one cow for 40 to 50 days (assuming 100 bushels per acre grain yield).
2. Two acres can carry one cow for 80 to 100 days (assuming 100 bushels per acre grain yield).
3. Cows will selectively graze the more palatable portions of the plant first: (1) grain; (2) leaves and husks; (3) cobs and stalks.
4. Using portable electric fences to rotationally graze the field will increase the value of the residue. Allow 0.5 acre per cow for each 25 days of grazing.
5. Expected recovery of residue by grazing is about 15 to 30 percent. If the potential yield of residue DM is 2 tons per acre, the recovery would be about 0.3 to 0.6 ton per acre.
6. Extremely thin cows should not graze cornstalks for more than 30 days.
7. For the first 30 days, a mineral supplement is adequate; for example, 40 percent trace mineral salt, 40 percent dicalcium phosphate and 20 percent vitamin A premix (5,000 IU per gram). After 30 days, a protein supplement that supplies 1/3 to 0.5 pound of actual protein per head daily with the mineral mix will be required.
1. Energy is marginally deficient for mature brood cows - 45 percent versus 50 percent total digestible nutrients (TDN) - and extremely deficient for growing-finishing cattle - 45 percent versus 70 percent TDN.
2. Crude protein (CP) is somewhat deficient for dry mature brood cows - 4 percent versus 6 percent - and extremely deficient for growing-finishing cattle - 4 percent versus 10 to 13 percent CP.
3. Calcium appears to be nearly adequate for most classes for cattle but should be added as a safety factor, especially for young stock, because of the variability of corn residue.
4. Phosphorus is deficient for all classes of cattle - 0.12 percent versus 0.16 to 0.3 percent.
5. Vitamins A and E should either be added to the corn residue diet or injected intramuscularly.
As noted earlier, an extended grazing plan can allow a change in the farm management plan to reduce or eliminate hay production on the farm. This will be particularly true for smaller herds, where the cost of machinery cannot be accounted for over fewer animal sales. For example, in a 30-cow herd there would typically be sales of 20 calves and two to three cows per year. If the cost of machinery to make hay is a conservative $15,000 (a portion of tractor use, mowers, rakes, balers, wagons), with an annualized cost of $600, this results in a cost per animal sold of over $27. Remember that this is just the cost of owning the equipment; you must also add the fuel and labor costs to harvest hay. Secondly, there is no control over the weather, so forage quality may or may not be optimum.
What are the options? The first is custom hay harvest. This issue is not without its problems, due to timing (everybody's hay will be ready to bale at the same time). One solution that seems to work is to utilize the dairy farm neighbor to make your hay early in the season before his alfalfa is ready to harvest. The tonnage will not be as high, but the feed quality will be significantly better, particularly if wrapping high-moisture bales is an option to eliminate the weather issue. Secondly, purchase all of the hay, since you will need less of it. This eliminates the need for haying equipment, and you can usually dictate the quality of the feed you are buying.
Extending the grazing season has some advantages for most beef cattle farms, but financial planning and grazing management will be the keys to success.
Dr. John Comerford is an associate
professor and extension beef specialist
at Pennsylvania State University.